Glass or plastic materials used for windows, mirrors, lenses, goggles, and facial masks or shields become foggy when they are exposed to high humidity and temperature, or used at interfacial boundaries with a large difference in temperature or humidity. Products exposed to such conditions include those used in medical, military and industrial safety applications. Fog is caused by the condensation of moisture on the surface. For example, exhaled air from a person wearing a safety shield could cause fogging. To reduce or eliminate this problem, antifog coatings are frequently needed.
Antifog coatings may also be needed for use on disposable items such as single-use facemasks, which typically are based on polymer film substrates. For these and other applications, it is desirable that cost be kept to a minimum, and therefore in-line application methods would in many cases be desirable in order to keep costs low. However, existing antifog compositions capable of providing suitable antifog properties are often not easily applied by in-line processes. There is a continuing need for antifog coatings, and methods of applying them, capable of addressing these needs.